US2017336461A1PendingUtilityA1
Internal transformer composite-defect fuzzy diagnostic method based on gas dissolved in oil
Est. expiryFeb 13, 2035(~8.6 yrs left)· nominal 20-yr term from priority
G01N 33/2841G01R 31/62H01F 27/402G01F 25/00G01R 31/027
33
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Abstract
A transformer internal composite defect fuzzy diagnosis method based on gas dissolved in oil, comprising: a step of acquiring monitoring data of volume concentrations of five types of monitored feature gas; a step of determining ratio codes; a step of modifying a three-ratio method; a step of fuzzifying a boundary range; a step of calculating probabilities of the ratio codes; a step of calculating a probability of occurrence of each defect fault; and finally obtaining a fault type of a transformer. The method has the beneficial effects that: the method is simple and easy to achieve, and particularly suitable for being applied to an on-line transformer state monitoring system; based on a concept of fuzzy logic, diagnosis of composite defects of the transformer under a complicated state and evaluation of the degree of severity can be achieved, and the problem of sudden change caused by criterion boundary absolutisation can be effectively avoided; and multi-feature information such as an attention value and a ratio of the gas dissolved in the oil are merged and analysed, thereby effectively improving the diagnosis reliability.
Claims
exact text as granted — not AI-modified1 . A fuzzy diagnosis method for transformer internal composite defect based on gas dissolved in oil, comprising the following steps:
(I) acquiring monitoring data of volumetric concentrations of five types of monitored characteristic gases, i.e., hydrogen, methane, ethane, ethylene and acetylene; calculating the sum of the volumetric concentrations of methane, ethane, ethylene and acetylene (i.e., volumetric concentration of total hydrocarbons) from the monitoring data; judging whether the monitoring data of the five types of characteristic gases or the volumetric concentration of total hydrocarbons exceeds an alert value, which is selected as per the Chinese Standard GB/T7252-2001; if the monitoring data or the volumetric concentration of total hydrocarbons exceeds the alert value, further diagnosis is required; in that case, going to step (II); otherwise judging that the transformer has no defect or fault, if the monitoring data and the volumetric concentration of total hydrocarbons are normal; (II) determining ratio codes:
first, the ratios are set as follows:
r
1
=
c
1
(
C
2
H
2
)
c
2
(
C
2
H
4
)
,
r
2
=
c
3
(
CH
4
)
c
4
(
H
2
)
,
r
3
=
c
2
(
C
2
H
4
)
c
5
(
C
2
H
6
)
,
r
4
=
c
1
(
C
2
H
2
)
c
5
(
C
2
H
6
)
×
c
2
(
C
2
H
4
)
c
1
(
C
2
H
2
)
=
r
3
×
c
2
(
C
2
H
4
)
c
1
(
C
2
H
2
)
,
wherein, c 1 (C 2 H 2 ), c 2 (C 2 H 4 ), c 3 (CH 4 ), c 4 (H 2 ) and c 5 (C 2 H 6 ) respectively represent the volumetric concentration of five types of characteristic gases (acetylene, ethylene, methane, hydrogen and ethane), in unit of μL/L;
then, the ratio codes are determined according to the following rules:
if r 1 <0.1, the ratio code of r 1 is 0; if 0.15_r 1 <1, the ratio code of r 1 is 1; if 5.1r 1 <3, the ratio code of r 1 is 1; if r 1 the ratio code of r 1 is 2;
if r 2 <0.1, the ratio code of r 2 is 1; if 0.1≦r 2 <1, the ratio code of r 2 is 0; if 15-r 2 <3, the ratio code of r 2 is 2; if the ratio code of r 2 is 2;
if r 3 <0.1, the ratio code of r 3 is 0; if 0.15r 3 <1, the ratio code of r 3 is 0; if 1.5r 3 <3, the ratio code of r 3 is 1; if r 3 ≧3, the ratio code of r 3 is 2;
if r 4 ≦1.5, the ratio code of r 4 is 0; if r 4 >1.5, the ratio code of r 4 is 1;
(III) Correcting the method for determining the types of transformer defects or faults on the basis of three ratios as specified in the Chinese Standard GB/T7252-2001:
based on the types of transformer defects or faults corresponding to the three ratio codes specified in the Chinese Standard GB/T 7252-2001, a ratio code 011 corresponding to the type of partial discharge defect or fault is added;
a fourth ratio r 4 is added on the basis of the three ratio codes; for the type of defect or fault with ratio code 101 diagnosed with the three-ratio method, if the transformer is judged as having a spark discharge defect or fault; if r 4 >1.5, the transformer is judged as having an arc discharge defect or fault;
thus, obtaining a method for judging the types of transformer defects or faults according to ratio codes as follows:
if the ratio code of r 1 is 0, the ratio code of r 2 is 1, the ratio code of r 3 is 0, 1 or 2, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is partial discharge;
if the ratio code of r 1 is 0, the ratio code of r 2 is 0, the ratio code of r 3 is 1, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is low-temperature overheat lower than 300□;
if the ratio code of r 1 is 0, the ratio code of r 2 is 2, the ratio code of r 3 is 0, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is low-temperature overheat lower than 300□;
if the ratio code of r 1 is 0, the ratio code of r 2 is 2, the ratio code of r 3 is 1, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is 300-700° C. moderate-temperature overheat;
if the ratio code of r 1 is 0, the ratio code of r 2 is 0 or 2, the ratio code of r 3 is 2, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is high-temperature overheat higher than 700□;
if the ratio code of r 1 is 2, the ratio code of r 2 is 0, 1 or 2, the ratio code of r 3 is 0, 1 or 2, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is spark discharge;
if the ratio code of r 1 is 1, the ratio code of r 2 is 0, the ratio code of r 3 is 1, and the ratio code of r 4 is 0, the type of transformer defect or fault is spark discharge;
if the ratio code of r 1 is 1, the ratio code of r 2 is 0, the ratio code of r 3 is 1, and the ratio code of r 4 is 1, the type of transformer defect or fault is arc discharge;
if the ratio code of r 1 is 1, the ratio code of r 2 is 0, 1 or 2, the ratio code of r 3 is 0 or 2, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is arc discharge;
if the ratio code of r 1 is 1, the ratio code of r 2 is 1 or 2, the ratio code of r 3 is 1, and the ratio code of r 4 is 0 or 1, the type of transformer defect or fault is arc discharge;
(IV)blurring the boundary ranges of the ratios r 1 , r 2 , r 3 and r 4 with a semi-Cauchy rising/falling function, and representing the rising edges and falling edges of the boundaries with the semi-Cauchy rising/falling function as follows:
μ
a
(
r
)
=
{
1
,
r
≤
A
1
1
+
(
A
-
r
a
)
2
,
others
μ
a
(
r
)
=
{
1
,
r
≥
A
1
1
+
(
A
-
r
a
)
2
,
others
wherein, μ d (r) is a falling edge function; μ a (r) is a rising edge function; A is a boundary parameter; a is a distribution parameter; the values of A and a are as follows:
the rising edge boundary parameter of r 1 is 0.08, and the corresponding distribution parameter is 0.01, the falling edge boundary parameter of r 1 is 3.1, and the corresponding distribution parameter is 0.1;
the rising edge boundary parameter of r 2 is 0.06, and the corresponding distribution parameter is 0.02;
the falling edge boundary parameter of r 2 is 0.6, and the corresponding distribution parameter is 0.2;
the rising edge boundary parameter of r 3 is 0.8, and the corresponding distribution parameter is 0.1;
the falling edge boundary parameter of r 3 is 3.6, and the corresponding distribution parameter is 0.3;
the boundary parameter of r 4 is 1.43, and the corresponding distribution parameter is 0.1;
(V) obtaining the probabilities of the cases that the ratio codes of the ratios r 1 , r 2 and r 3 are 0, 1 and 2 respectively and the probabilities of the cases that the ratio code of r 4 is 0 or 1 respectively, with the semi-Cauchy rising/falling function; the expressions are as follows:
Probability f-code0(r 1 ) of the case that the ratio code of r 1 is 0:
f
-
code0
(
r
1
)
=
{
1
(
r
1
≤
0.08
)
1
1
+
(
0.08
-
r
1
0.01
)
2
(
r
1
>
0.08
)
Probability f-code1(r 1 ) of the case that the ratio code of r 1 is 1:
f
-
code
1
(
r
1
)
=
{
1
1
+
(
0.08
-
r
1
0.01
)
2
(
r
1
≤
0.08
)
1
(
0.08
≤
r
1
≤
3.1
)
1
1
+
(
3.1
-
r
1
0.1
)
2
(
r
1
>
3.1
)
probability f-code2(r 1 ) of the case that the ratio code of r 1 is 2:
f
-
code
2
(
r
1
)
=
{
1
1
+
(
3.1
-
r
1
0.1
)
2
(
r
1
<
3.1
)
1
(
r
1
≥
3.1
)
probability f-code0(r 2 ) of the case that the ratio code of r 2 is 0:
f
-
code
0
(
r
2
)
=
{
1
1
+
(
0.06
-
r
2
0.02
)
2
(
r
2
<
0.06
)
1
(
0.06
≤
r
2
≤
0.6
)
1
1
+
(
0.06
-
r
2
0.02
)
2
(
r
2
>
0.6
)
probability f-code1(r 2 ) of the case that the ratio code of r 2 is 1:
f
-
code
1
(
r
2
)
=
{
1
(
r
2
≤
0.06
)
1
+
(
0.06
-
r
2
0.02
)
2
(
r
2
>
0.06
)
probability f-code2(r 2 ) of the case that the ratio code of r 2 is 2:
f
-
code
2
(
r
2
)
=
{
1
1
+
(
0.6
-
r
2
0.2
)
2
(
r
2
<
0.6
)
1
(
r
2
≥
0.6
)
probability f-code0(r 3 ) of the case that the ratio code of r 3 is 0:
f
-
code
0
(
r
3
)
=
{
1
(
r
3
≤
0.8
)
1
1
+
(
0.8
-
r
3
0.1
)
2
(
r
3
>
0.8
)
probability f-code1(r 3 ) of the case that the ratio code of r 3 is 1:
f
-
code
1
(
r
3
)
=
{
1
1
+
(
0.6
-
r
3
0.1
)
2
(
r
3
<
0.8
)
1
(
0.8
≤
r
3
≤
3.6
)
1
1
+
(
3.6
-
r
3
0.3
)
2
(
r
3
>
3.6
)
probability f-code2(r 3 ) of the case that the ratio code of r 3 is 2:
f
-
code
2
(
r
3
)
=
{
1
1
+
(
3.6
-
r
3
0.3
)
2
(
r
3
>
3.6
)
1
(
0.8
≤
r
3
≤
3.6
)
probability f-code0(r 4 ) of the case that the ratio code of r 4 is 0:
f
-
code
0
(
r
4
)
=
{
1
(
r
4
≤
1.43
)
1
1
+
(
1.43
-
r
4
0.1
)
2
(
r
4
>
1.43
)
Probability f-code1(r 4 ) of the case that the ratio code of r 4 is 1:
f
-
code
1
(
r
4
)
=
{
1
1
+
(
1.43
-
r
4
0.1
)
2
(
r
4
<
1.43
)
1
(
r
4
≥
1.43
)
(VI)representing the probabilities of ratio codes with maximum value logic and minimum value logic, and thereby obtaining a fuzzy multi-value form of the diagnostic result of the types of transformer defects or faults; the probabilities of the types of transformer defects or faults are as follows:
f (partial discharge)=min[ f -code0( r 1 ), f -code1(r 2 )];
f (low-temperature overheat)=max{min[ f -code0(r 1 ), f -code0(r 2 ), f -code1(r 3 )], min[ f -code0(r 1 ),
f-code2( r 2 ), f -code0( r 3)]};
f (moderate-temperature overheat)=min[ f -code0( r 1 ), f -code2( r 2 ), f -code1( r 3)];
f (high-temperature overheat)=max{min[ f -code0( r 1 ), f -code0( r 2 ), f -code2( r 3 )], min[ f -code0( r 1 ), f -code2( r 2), f -code2( r 3 )]};
f (spark discharge)=max{ f -code2( r 1 ), min[ f -code 1( r 1 ), f -code0( r 2 ), f -code1( r 3 ), f -code0( r 4 )]};
f (arc discharge)=max{min[ f -code 1( r 1 ), f -code0( r 2 ), f -code1( r 3 ), f -code1( r 4 )], min[ f -code1( r 1 ), f -code0( r 3 )], min[ f -code 1( r 1 ), f -code2( r 3 )], min [ f -code1( r 1 ), f -code1( r 2 ), f -code1( r 3 )], min[ f -code 1( r 1 ), f -code2( r 2 ), f -code 1( r 3 )]}.Cited by (0)
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